<h1 id="hawaii-congressional-districts">2020 Hawaii Congressional
Districts</h1>
<h2 id="redistricting-requirements">Redistricting requirements</h2>
<p>In Hawaii, under <a
href="https://www.capitol.hawaii.gov/hrscurrent/Vol01_Ch0001-0042F/HRS0025/HRS_0025-0002.htm">HRS
Title 1 S25</a>, districts must:</p>
<ol type="1">
<li>be contiguous unless crossing islands (25-2 (b) (2))</li>
<li>be geographically compact (25-2(b)(3))</li>
<li>preserve tract boundaries as much as possible (25-2(b)(4))</li>
<li>not unduly favor any people or party (25-2(b)(6))</li>
<li>avoid mixing substantially different socioeconomic regions
(25-2(b)(6))</li>
</ol>
<h3 id="algorithmic-constraints">Algorithmic Constraints</h3>
<p>We enforce a maximum population deviation of 0.5%. We use Census
tracts are in accordance with (25-2(b)(4)). We use municipalities to
attempt to follow (25-2(b)(6)) in absence of regional knowledge.</p>
<h2 id="data-sources">Data Sources</h2>
<p>Data for Hawaii comes from the ALARM Project’s <a
href="https://alarm-redist.github.io/posts/2021-08-10-census-2020/">2020
Redistricting Data Files</a>.</p>
<h2 id="pre-processing-notes">Pre-processing Notes</h2>
<p>Islands are connecting in the adjacency graph, but this is not used
for simulation purposes.</p>
<h2 id="simulation-notes">Simulation Notes</h2>
<p>We sample 5,000 districting plans for Hawaii across 2 independent
runs of the SMC algorithm. We use partial SMC to draw one district in
the contiguous portion of Honolulu and assign the remainder to district
2. We use municipalities (or the county name if a tract is not assigned
to a municipality) for the algorithmic constraint.</p>
<h2 id="contents">Contents</h2>
<ul>
<li><code>HI_cd_2020_stats.csv</code> contains summary statistics on the
sampled redistricting plans</li>
<li><code>HI_cd_2020_plans.rds</code> is a compressed
<code>redist_plans</code> object, which contains the matrix of
precinct/block assignments and may be used for further analysis.</li>
<li><code>HI_cd_2020_map.rds</code> is a compressed
<code>redist_map</code> object, which contains the precinct/block
shapefile and demographic data.</li>
</ul>
<p>Both the <code>redist_plans</code> and <code>redist_map</code> object
are intended to be used with the <a
href="https://alarm-redist.github.io/redist/">redist package</a>.</p>
<h3 id="codebook-for-summary-statistics">Codebook for summary
statistics</h3>
<ul>
<li><code>draw</code>: unique identifier for each sample. Non-numeric
draw names are real-world plans, e.g., <code>cd_2010</code> for an
enacted 2010 plan.</li>
<li><code>district</code>: a district identifier. District numbers
roughly match those in the enacted plan, but the correspondence is not
perfect.</li>
<li><code>chain</code>: a number identifying the run of the
redistricting algorithm used to produce this draw. Used for diagnostic
purposes.</li>
<li><code>pop_overlap</code>: a number indicating the fraction of people
in this plan who reside in the same-numbered district in the enacted
plan.</li>
<li><code>total_pop</code>: the total population of each district.</li>
<li><code>total_vap</code>: the total voting-aged population of each
district.</li>
<li><code>pop_*</code>, <code>vap_*</code>: total (voting-aged)
population within racial and ethnic groups for each district. Variable
codes documented <a
href="https://github.com/alarm-redist/census-2020#data-format">here</a>.</li>
<li><code>plan_dev</code>: the maximum population deviation among
districts in the plan. Computed as
<code>max(abs(distr_pop - target_pop)/target_pop)</code>.</li>
<li><code>comp_edge</code>: compactness, as measured by the fraction of
internal edges kept. Higher values indicate more compactness.</li>
<li><code>comp_polsby</code>: compactness, as measured by the
Polsby-Popper score. Higher values indicate more compactness.</li>
<li><code>county_splits</code>: the number of counties which belong to
more than one district.</li>
<li><code>muni_splits</code>: the number of Census Designated Places
which belong to more than one district.</li>
<li><code>*_##_dem_*</code>, <code>*_##_rep_*</code>: vote counts for
statewide Democratic and Republican candidates in a certain election.
More information <a
href="https://github.com/alarm-redist/census-2020#data-format">here</a>.</li>
<li><code>adv_##</code>, <code>arv_##</code>: average vote counts for
statewide Democratic and Republican candidates in a certain year. More
information <a
href="https://github.com/alarm-redist/census-2020#data-format">here</a>.</li>
<li><code>ndv</code>, <code>nrv</code>: averages of the
<code>adv_##</code> and <code>arv_##</code> variables across all
available elections.</li>
<li><code>ndshare</code>: normal Democratic share, computed as
<code>ndv / (ndv + nrv)</code></li>
<li><code>e_dvs</code>: average Democratic vote share, computed as the
average of the Democratic vote share when first scored under each
statewide election.</li>
<li><code>pr_dem</code>: probability seat is represented by a Democrat;
calculated as the fraction of statewide elections under which the
district had a majority Democratic share.</li>
<li><code>e_dem</code>: expected number of Democratic seats for the
plan; equivalent to summing the <code>pr_dem</code> values across
districts</li>
<li><code>pbias</code>: partisan bias at 50% vote share, averaged across
all available elections. Positive values indicate Republican bias.</li>
<li><code>egap</code>: the efficiency gap, averaged across all available
elections. Positive values indicate Republican bias.</li>
</ul>
